Some embodiments described herein relate generally to methods and apparatus for implementing virtual soft handoff from one wireless interface to another wireless interface in wireless devices which can allow for efficient operation of applications including, for example, voice applications and video applications, with a high quality of service and with minimal or no disruptions in connectivity.
Wireless devices such as portable handsets have the ability to connect to multiple network interfaces having different layer-2 (L2) protocols. Such a wireless device can have for example an Institute of Electrical and Electronics Engineers Inc. (IEEE) 802.11 wireless interface, and a third generation mobile telecommunications (3G) or a fourth generation mobile telecommunications (4G) cellular interface. A robust wireless communication system for such a wireless device needs to maintain a high quality of service (QoS) with minimal or no disruptions in connectivity, for both voice applications and video applications. Additionally, wireless voice applications and video applications are typically implemented with internet protocol (IP) address preservation so that network features such as routing, basic firewall, traffic management, etc. can function properly.
To achieve a robust wireless communication system with high QoS, handoff within a wireless device from one wireless interface to another should typically be performed while maintaining a minimal level of QoS and minimal disruption of connectivity. Some known handoff techniques called “soft handoff” are employed today in cellular applications at a physical layer, whereby signals from multiple base stations are combined to create a more robust signal that can be recovered. Additionally, other known handoff techniques from a cellular interface to a Wireless Fidelity (WiFi) interface exist that can be classified as “hard handoff” techniques. Hard handoff techniques involve switching a device from being connected to a cellular network to being connected to a WiFi network at a given point in time.
Accordingly, a need exists for methods and apparatus for implementing a virtual soft handoff technique involving multiple different network connections. Moreover, a need exists to combine reception from multiple networks to ensure a more robust “virtual link” between the source device and the destination device during the handoff process between networks. Such methods and apparatus can help ensure a lossless handoff where both networks are used during the transition between the networks.